You forgot the real ruby turned into a villain. Besides, everyone has different reaction to abuse. This is just Cesare's way. I have no info about the real ruby but the transmigrator had at least a good person by her side until that person (her sister) died. Cesare was not love since the beginning, especially when he was still young, when his mind is still very impressionable. ┗( T﹏T )┛

No wonder he punish Ruby all the time while saying he loves her. He got his twisted personality because of the pope and his mother's neglect.